98 Plant Life and Evolution 



directly from the earth, and the sporophyte for the 

 first time assumes the form of an entirely inde- 

 pendent plant. For a greater or less time, however, 

 it remains attached to the gametophyte and develops 



FIG. ii 



A Gametophyte, g, of a fern, Danaea, bearing two young 

 sporophytes, sp. Each sporophyte has produced a leaf above 

 and a root, r, below. 



B Gametophyte of a liverwort, Megaceros, with two sporo- 

 phytes ; the latter, unlike those of the fern, have no root. 



a foot very similar in structure and function to that 

 found in the sporophyte of the bryophytes. 



The Gametophyte of the Fern. If the spores of 

 a fern are sown upon moist earth, there will pres- 

 ently be developed a little green thallus, the gameto- 

 phyte (Fig. ii, A, g), which does not in the least 

 resemble a fern, but in appearance is very much 

 like some of the simpler liverworts, and has its near- 

 est analogue perhaps in the horned liverworts, whose 

 reproductive organs, both antheridium and arche- 



